1. Field of the Invention
The present invention relates to a display device.
2. Description of the Related Art
In recent years, a display device such as an organic EL display device that uses an organic EL (Electro-Luminescent) element and a liquid crystal display device is put into practical use. However, since the organic EL element is susceptible to moisture, the organic EL element deteriorates due to moisture and a lighting defect such as a dark spot is supposed to be generated. Further, on a liquid crystal display device as well, there has been occurring a problem that a property of a thin film transistor varies by being influenced by infiltrated moisture and degeneration of a display quality occurs.
Regarding such issues, Japanese Unexamined Patent Publication No. 2007-264354 discloses that a driving circuit including a thin film transistor and the like, an insulating film to cover the driving circuit, and a planarizing film to planarize unevenness caused by a surface shape of the driving circuit are provided on an element substrate, and a sealing layer is formed at an interface between the planarizing film and the insulating film located an edge part of the planarizing film, to thereby favorably prevent an infiltration of moisture into the interface.
Further, Japanese Unexamined Patent Publication No. 2014-142641 discloses that on a display device on which a transistor including an oxide semiconductor layer is provided, when manufacturing the transistor, a heat treatment is applied to the oxide semiconductor layer, and dehydration is performed through the heat treatment.